45 resultados para electro-optic modulator


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AIMS: To compare morphometric parameters and diagnostic performance of the new Stratus Optical Coherence Tomograph (OCT) Disc mode and the Heidelberg Retina Tomograph (HRT); to evaluate OCT's accuracy in determining optic nerve head (ONH) borders. METHODS: Controls and patients with ocular hypertension, glaucoma-like discs, and glaucoma were imaged with OCT Disc mode, HRT II, and colour disc photography (DISC-PHOT). In a separate session, automatically depicted ONH shape and size in OCT were compared with DISC-PHOT, and disc borders adjusted manually where required. In a masked fashion, all print-outs and photographs were studied and discs classified as normal, borderline, and abnormal. The Cohen kappa method was then applied to test for agreement of classification. Bland-Altman analysis was used for comparison of disc measures. RESULTS: In all, 49 eyes were evaluated. Automated disc margin recognition failed in 53%. Misplaced margin points were more frequently found in myopic eyes, but only 31/187 were located in an area of peripapillary atrophy. Agreement of OCT with photography-based diagnosis was excellent in normally looking ONHs, but moderate in discs with large cups, where HRT performed better. OCT values were consistently larger than HRT values for disc and cup area. Compared with HRT, small rim areas and volumes tended to be minimized by OCT, and larger ones to be magnified. CONCLUSIONS: Stratus OCT Disc protocol performed overall well in differentiating between normal and glaucomatous ONHs. However, failure of disc border recognition was frequently observed, making manual correction necessary. ONH measures cannot be directly compared between HRT and OCT.

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PURPOSE: To analyze how far an ischemic component might have been involved in optic neuritis. METHODS: Case report: a 32-year-old man with symptoms characteristic for optic neuritis underwent extensive clinical, laboratory/serological and vascular examination for systemic associations and vascular involvement. RESULTS: The patient was found to have a temporary ocular blood flow dysregulation and increased plasma endothelin-1 levels which decreased after the acute phase of the optic nerve. CONCLUSIONS: We conclude that there might be an ischemic component in this patient with optic neuritis and hypothesize that this ischemic component is at least in part due to a temporarily increased endothelin-1 level.

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OBJECTIVES: To determine the incidence of optic disc swelling as a possible indicator of cerebral edema in a large group of healthy mountaineers exposed to very high altitudes and to correlate these findings with various clinical and environmental factors and occurrence of acute mountain sickness and high-altitude cerebral edema. METHODS: This multidisciplinary, prospective, observational cohort study was performed in 2005 within the scope of a medical research expedition to Muztagh Ata (7546 m [24,751 ft]) in Western Xinjiang Province, China. Twenty-seven healthy mountaineers aged 26 to 62 years participated. Medical examinations were performed in Switzerland 1 month before and 4 1/2 months after the expedition. Ophthalmologic examinations were performed at 4 high camps (maximum elevation, 6865 m [22,517 ft]). Optic disc status was documented using digital photography. Further assessments included arterial oxygen saturation and cerebral acute mountain sickness scores. RESULTS: Sixteen of 27 study subjects (59%) exhibited optic disc swelling during their stay at high altitudes, with complete regression on return to lowlands. Significant correlation was noted between optic disc swelling and lower arterial oxygen saturation (odds ratio, 0.86 per percentage of arterial oxygen saturation; 95% confidence interval, 0.81-0.92; P < .001), younger age (odds ratio, 0.95 per year; 95% confidence interval, 0.90-0.99; P = .03), and higher cerebral acute mountain sickness scores (odds ratio, 2.32 per 0.1 point; 95% confidence interval, 1.48-3.63; P < .001). CONCLUSION: Optic disc swelling occurs frequently in high-altitude climbers and is correlated with peripheral oxygen saturation and symptoms of acute mountain sickness. It is most likely the result of hypoxia-induced brain volume increase.

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To analyze the impact of opacities in the optical pathway and image compression of 32-bit raw data to 8-bit jpg images on quantified optical coherence tomography (OCT) image analysis.

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BACKGROUND: Polycythemia vera (PV) is a hemopoetic disorder. Apparently, although thrombosis accounts for the majority of morbidity, AION has not been associated with PV so far. PATIENT AND FINDINGS: A 63 y-old woman with PV was hospitalized because of acute liver failure. She also experienced bilateral painless loss of vision. Bilateral, pale optic disc swelling with flame-like hemorrhages, more pronounced in the right eye, constricted visual fields, and relative afferent papillary defect (RAPD) on the right side were present. Computer tomography scan revealed no signs of intraorbital pathology, elevated intracranial pressure or hemorrhages. CLINICAL COURSE: We interpreted the findings as AION associated with the hyperviscosity syndrome. Liver transplantation had to be carried out in the next days. Three weeks later, vision improved slightly, but RAPD persisted, and disc pallor developed in both eyes. The patient died two months later. DISCUSSION: Central retinal artery and vein occlusions have been described as complications of Essential thrombocythemia, but not of PV. We observed a rare case of bilateral neuropathy suggestive of AION. This condition has so far not been associated with PV.

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We carried out a comprehensive study of Au(1 1 1) oxidation–reduction in the presence of (hydrogen-) sulfate ions on ideally smooth and stepped Au(S)[n(1 1 1)-(1 1 1)] single crystal electrodes using cyclic voltammetry, in situ scanning tunneling microscopy (STM) and vibration spectroscopy, such as surface-enhanced infrared absorption spectroscopy (SEIRAS) and shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Surface structure changes and the role of surface defects in the potential regions of double layer charging and gold oxidation/reduction are discussed based on cyclic voltammetry and in situ STM data. SEIRAS and SHINERS provide complementary information on the chemical nature of adsorbates. In particular, the potential-dependent formation and stability ranges of adsorbed sulfate, hydroxide-species and of gold surface oxide could be resolved in detail. Based on our experimental observations, we proposed new and extended mechanisms of gold surface oxidation and reduction in 1.0 M H2SO4 and 1.0 M Na2SO4.

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PURPOSE To investigate retrograde axonal degeneration for its potential to cause microcystic macular edema (MME), a maculopathy that has been previously described in patients with demyelinating disease. To identify risk factors for MME and to expand the anatomic knowledge on MME. DESIGN Retrospective case series. PARTICIPANTS We included 117 consecutive patients and 180 eyes with confirmed optic neuropathy of variable etiology. Patients with glaucoma were excluded. METHODS We determined age, sex, visual acuity, etiology of optic neuropathy, and the temporal and spatial characteristics of MME. Eyes with MME were compared with eyes with optic neuropathy alone and to healthy fellow eyes. With retinal layer segmentation we quantitatively measured the intraretinal anatomy. MAIN OUTCOME MEASURES Demographic data, distribution of MME in the retina, and thickness of retinal layers were analyzed. RESULTS We found MME in 16 eyes (8.8%) from 9 patients, none of whom had multiple sclerosis or neuromyelitis optica. The MME was restricted to the inner nuclear layer (INL) and had a characteristic perifoveal circular distribution. Compared with healthy controls, MME was associated with significant thinning of the ganglion cell layer and nerve fiber layer, as well as a thickening of the INL and the deeper retinal layers. Youth is a significant risk factor for MME. CONCLUSIONS Microcystic macular edema is not specific for demyelinating disease. It is a sign of optic neuropathy irrespective of its etiology. The distinctive intraretinal anatomy suggests that MME is caused by retrograde degeneration of the inner retinal layers, resulting in impaired fluid resorption in the macula.

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A 44-year-old male European with type I diabetes mellitus fell into diabetic ketoacidosis. In the emergency room, he developed an episode of asystole and respiratory failure requiring one cycle of cardiopulmonary resuscitation and extracorporeal membrane oxygenation (ECMO). Waking up 7 days later, he presented a bilateral complete loss of vision. Ophthalmological examination including funduscopy on days 1 and 10, after extubation, showed bilateral large round pupils non-reactive to light and a normal fundus. Neuroimaging studies, including MRI and MRA of the brain, were all within normal limits. A lumbar puncture and comprehensive serological testing excluded an infectious or rheumatic cause. An empirical high-dose intravenous steroid treatment administered for 5 days had no effect on his vision. His eye examination at 1.5 months follow-up showed a normal fundus except for progressive bilateral optic nerve disc pallor, which pointed towards the diagnosis of a posterior ischaemic optic neuropathy.

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OBJECTIVE To assess the efficacy and safety of sono-electro-magnetic therapy compared to placebo in men with refractory CPPS. PATIENTS AND METHODS In a randomized, placebo-controlled, double-blind single center trial, we assessed the effect of sono-electro-magnetic therapy in men with treatment refractory CPPS. Sixty male patients were randomly assigned to treatment with either sono-electro-magnetic (n = 30) or placebo therapy (n = 30) for 12 weeks. The primary outcome was a change in the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) from baseline to 12 weeks. RESULTS The 12-week difference between sono-electro-magnetic and placebo therapy in changes of the NIH-CPSI total score was -3.1 points (95% CI -6.8 to 0.6, p = 0.11). In secondary comparisons of NIH-CPSI sub-scores, we found differences between groups most pronounced for the quality-of-life sub-score (difference at 12 weeks -1.6, 95% CI -2.8 to -0.4, p = 0.015). In stratified analyses, the benefit of sono-electro-magnetic therapy appeared more pronounced among patients who had a symptom duration of 12 months or less (difference in NIH-CPSI total score -8.3, 95% CI -14.5 to 2.6) than in patients with a longer symptom duration (-0.8, 95% CI -4.6 to 3.1; p for interaction = 0.023). CONCLUSIONS Sono-electro-magnetic therapy did not result in a significant improvement of symptoms in the overall cohort of treatment refractory CPPS patients compared to placebo treatment. Subgroup analysis indicates, however, that patients with a symptom-duration of 12 months or less may benefit from sono-electro-magnetic therapy, warranting larger randomized controlled trials in this subpopulation. TRIAL REGISTRATION ClinicalTrials.gov NCT00688506.

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BACKGROUND It has been suggested that sleep apnea syndrome may play a role in normal-tension glaucoma contributing to optic nerve damage. The purpose of this study was to evaluate if optic nerve and visual field parameters in individuals with sleep apnea syndrome differ from those in controls. PATIENTS AND METHODS From the records of the sleep laboratory at the University Hospital in Bern, Switzerland, we recruited consecutive patients with severe sleep apnea syndrome proven by polysomnography, apnea-hypopnea index >20, as well as no sleep apnea controls with apnea-hypopnea index <10. Participants had to be unknown to the ophtalmology department and had to have no recent eye examination in the medical history. All participants underwent a comprehensive eye examination, scanning laser polarimetry (GDx VCC, Carl Zeiss Meditec, Dublin, California), scanning laser ophthalmoscopy (Heidelberg Retina Tomograph II, HRT II), and automated perimetry (Octopus 101 Programm G2, Haag-Streit Diagnostics, Koeniz, Switzerland). Mean values of the parameters of the two groups were compared by t-test. RESULTS The sleep apnea group consisted of 69 eyes of 35 patients; age 52.7 ± 9.7 years, apnea-hypopnea index 46.1 ± 24.8. As controls served 38 eyes of 19 patients; age 45.8 ± 11.2 years, apnea-hypopnea index 4.8 ± 1.9. A difference was found in mean intraocular pressure, although in a fully overlapping range, sleep apnea group: 15.2 ± 3.1, range 8-22 mmHg, controls: 13.6 ± 2.3, range 9-18 mmHg; p<0.01. None of the extended visual field, optic nerve head (HRT) and retinal nerve fiber layer (GDx VCC) parameters showed a significant difference between the groups. CONCLUSION Visual field, optic nerve head, and retinal nerve fiber layer parameters in patients with sleep apnea did not differ from those in the control group. Our results do not support a pathogenic relationship between sleep apnea syndrome and glaucoma.